NWS New York, NY wrote its last area forecast discussion before the first event at Jan 23, 6:52 AM EST, 2 hours 8 minutes earlier.
Area forecast discussion, Jan 23, 6:52 AM EST, 2 hours 8 minutes before
Area Forecast Discussion
National Weather Service New York NY
652 AM EST Mon Jan 23 2017
.SYNOPSIS...
Strong low pressure over the Tennessee Valley this morning
will emerge off the Mid Atlantic this afternoon becoming a major
coastal storm as it tracks slowly northeast. The low passes to
the south and east of Long Island Tuesday into Tuesday night. High
pressure will build in the wake of the storm on Wednesday. A
series of weak, mainly dry cold fronts will move southeast around
low pressure north of New England through Sunday.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Minor adjustments this update to account for drizzle this morning
and to initialize with latest observations.
A strong southern branch upper low over the Tennessee Valley this
morning will send a deepening surface low off the Mid Atlantic
coast this afternoon. The low will work slowly north and east
through Tuesday, passing south and east of New England. At the
same time, a departing northern branch upper trough across eastern
Canada will be followed by strong surface high pressure. This will
set the stage for strong Northeast winds, heavy precipitation,and
urban, small stream, and coastal flooding.
Models are in good overall agreement with the track and intensity
of the low with some small differences. The biggest concern
relates to thermodynamics with the cold air drainage ahead of the
storm through tonight, and then warming aloft as the low wraps in
warmer air off the Atlantic. The timing of the warming could have
significant consequences for areas well north and west of NYC
which are under a Winter Weather Advisory. Those areas will
likely see a light mix of rain and sleet today, with mainly rain
elsewhere. The low continues to trend slower, thus the delay in
heavy precipitation to late this afternoon into this evening.
Rainfall amounts today may approach a quarter inch by evening.
The main story is going to be high winds, specifically at the
coast which could see gusts up to 60 mph by late afternoon. An
anomalously strong easterly jet will gradually strengthen ahead
of the low, peaking at around 70 kt at 925 mb just south of LI
this evening. The NAM is strongest with the jet and is preferred
in this scenario. Thermo profiles shows mixing up to 925 mb,
which supports a good percentage of these winds mixing down to the
surface. High Wind Warnings remain up at the coast, with Wind
Advisories up for much of the interior.
A strong cold air damming signature on the east side of the
Appalachians with a strong NE flow will allow for temperatures to
gradually fall today, with most locations into the mid and upper
30s by late this morning. Mid level dry air and wet bulb
temperatures near or below zero in the interior will allow for
some sleet to mix in with any light rain.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
Best thermal forcing and dynamics will be across the area the
first half of tonight with heavy precipitation and high winds.
There is the potential for in 1 to 1 1/2 inches of rainfall
by early morning, with the rain decreasing in intensity toward
daybreak.
A Flood Watch remains up for the NYC metro, southern portions of
the Lower Hudson Valley, and coastal SW Connecticut. This is
mainly for urban and small stream flooding concerns, especially if
localized rainfall amounts exceed 3 inches. In addition, should
the heavy rain coincide with the high tide, this will exacerbate
any flooding. This includes locations along tidally affected
rivers, such as the Passaic, Hackensack, and Hudson.
As previously mentioned. temperature profiles will be critical to
the northwest of NYC, as the heavy precipitation falls in a
marginally cold airmass. Deep-layered lift and column cooling
will result in a period of moderate to heavy snow across portions
of Orange and Putnam counties in the Lower Hudson Valley, and
western Passaic in Northeast NJ. Eventually, enough warm air aloft
comes in late tonight for a transition back to rain. Timing is
everything here. Should the heavy precipitation fall as snow for
a longer period of time, snowfall totals would be higher than
currently forecast, and vice versa if more as rain. Right now,
those locations under a winter weather advisory are forecast to
see 2 to 4 inches of snow and sleet with perhaps a light coating
of ice.
Winds and heavy precip should fall off late tonight with some
rain lingering into Tuesday as the low has trended slower in the
models. The slow moving storm will pass on Tuesday.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Tuesday night until Midnight...Light precipitation will end from
west to east as low pressure moves east of coastal New England.
The highest chc for mixed precip will be across our far west zones
and across higher elevations NW of NYC. However, we are not
anticipating any significant accumulations.
Wednesday and Thursday...A weak ridge of high pressure will move
quickly east across the region early Wednesday followed by a long
wave of low pressure thru the day Thursday. No sensible weather is
forecast as temps cont to avg above normal in SW flow.
Friday through Sunday...signals a weather pattern change as a ridge
builds across western North America and a trough develops across the
Eastern U.S. This will bring colder temps across the area to close
out January.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
A deep low centered over the southeastern states will track slowly
to the northeast today, emerging off the Mid Atlantic coast by 00Z
Tuesday. The low then tracks slowly northward along the coast Monday
night.
Winds will be the primary issue through the TAF period. Northeast
winds will increase throughout the day, peaking at around 30 kt
sustained, with gusts to 45-50 kt late this afternoon into this
evening. There is a chance of occasional gusts to near 60 kt at
coastal terminals this afternoon and this evening. Winds will
begin to slowly diminish after 00Z and become more northerly as
the low passes to the south and east.
While the bulk of the precipitation should hold off until after 18Z
on Monday, with plenty of low level moisture light rain or drizzle
is likely at times Monday morning. Precipitation will fall in the
form of rain for the city and coastal terminals, with an outside
chance of rain mixing with sleet as precipitation starts this
afternoon at KHPN. Rain could be heavy at times tonight. At KSWF, a
mix of rain and sleet is possible to start, becoming a mix of heavy
snow and sleet late in the day. Snow and sleet could total 1 to 2
inches by tonight, with higher accumulations possible if the
precipitation falls primarily as snow.
Primarily MVFR ceilings this morning will persist into the
afternoon before falling to IFR as the rain moves in and becomes
heavy late this afternoon and this evening.
NY Metro Enhanced Aviation Weather Support...
Detailed information, including hourly TAF wind component forecasts,
can be found at: http:/www.weather.gov/zny/n90
KJFK TAF Comments: Amendments possible this morning for changes in
ceiling. Occasional gusts to near 60 kt are possible this afternoon
and evening.
KLGA TAF Comments: Amendments possible this morning for changes in
ceiling.
KEWR TAF Comments: Amendments possible this morning for changes in
ceiling.
The afternoon KEWR haze potential forecast is YELLOW...which implies
slant range visibility 4-6SM outside of cloud.
KTEB TAF Comments: Amendments possible this morning for changes in
ceiling.
KHPN TAF Comments: Amendments possible this morning for changes in
ceiling.
KISP TAF Comments: Amendments possible this morning for changes in
ceiling. Occasional gusts to near 60 kt are possible this afternoon
and evening.
.OUTLOOK FOR 12Z TUESDAY THROUGH FRIDAY...
.Tuesday-Tuesday night...IFR ceilings to start. Rain will come to
an end beginning late Tuesday afternoon with conditions improving
during the evening to VFR southwest to northeast. Winds NE backing
to NW during the day.
.Wednesday and Thursday...VFR. SW Winds 15-25 kt.
.Friday...VFR. W 15-25 kt.
&&
.MARINE...
An intensifying storm moving up the coast will bring storm to
marginal hurricane force wind gusts to the ocean waters late this
afternoon into this evening. On the non-ocean waters, storm
warnings remain in effect. Expect peak winds 50-60 kt where storm
warnings remain. Before then, gales are likely to develop quickly
tonight, followed by storm force winds developing from south to
north through the day on Monday.
Max seas could peak at 20-22 ft on the ocean, 9-12 ft from Orient
Point east, and 8-9 ft on central Long Island Sound, per combo of
WaveWatch/NWPS guidance and wind/wave climatology.
Marine Long Term...
.Tuesday through Wednesday Afternoon...Seas will gradually
subside as winds become SW at 15-20kt by Wednesday Afternoon.
.Wednesday Night...Winds and seas decrease below Small Craft
Advisory levels.
.Thursday and Friday...Winds and seas increase to SCA on the Ocean
with the approach and passage of a cold front.
&&
.HYDROLOGY...
QPF late today through tonight will likely be in the 1-2 inch
range, with locally higher amounts possible with the heaviest
rainfall. If high end rainfall amounts are realized, this will
bring a threat for moderate urban flooding and minor small stream
flooding in NE NJ and the Lower Hudson Valley. This will be
exacerbated by coincidence of high tide with heavy rain Mon eve
along coastal waterfront and shoreline roads...including along
tidally affected rivers. Potential for minor flooding on larger
rivers is slight.
&&
.TIDES/COASTAL FLOODING...
Coastal flood advisory early this morning remains in effect for the
south shore bays of Long Island. Do not expect thresholds to be met
elsewhere.
For the late afternoon/evening tide, expect widespread minor to
areas of moderate coastal flooding.
Primary attention remains for the late afternoon/evening high tide
cycle. Moderate coastal flooding expected along southern and eastern
bays of LI, Staten Island, low-lying north and east facing
coastlines along Western LI Sound, and the Atlantic beachfront due
to the combination of elevated water levels and wave action. There
is a low potential for major flood thresholds to be reached in the
most vulnerable Great South Bay communities such as Lindenhurst and
Freeport. A coastal flood warning remains in effect to address this
flood threat. Elsewhere minor to locally moderate coastal flooding
expected.
Minor to locally moderate coastal flooding could linger for the
southern and eastern bay areas for the Tuesday morning high tide
cycle as well, including the lower NY Harbor.
An ensemble of guidances is showing potential for surge to build to
3 1/2 to 4 1/2 ft by this evening. These latest numbers are close to
yesterday's guidance, with some differences noted in a few spots.
The evening expected surge is in line with surges seen during a
March 13th 2010 event with similarities in wind/wave forcing.
The other concern will be for widespread dune erosion and localized
washovers at Atlantic ocean beaches from elevated waters levels
and an east to west sweep of 8 to 14 ft surf today into Tue.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...High Wind Warning until 1 AM EST Tuesday for CTZ009>012.
Flood Watch from 1 PM EST this afternoon through late tonight
for CTZ009.
Wind Advisory until 1 AM EST Tuesday for CTZ005>008.
Coastal Flood Advisory from 5 PM this afternoon to 11 PM EST
this evening for CTZ009>012.
NY...High Wind Warning until 1 AM EST Tuesday for NYZ071>075-
078>081-176>179.
Coastal Flood Warning from 3 PM this afternoon to 11 PM EST
this evening for NYZ079>081-179.
Winter Weather Advisory from 1 PM this afternoon to 7 AM EST
Tuesday for NYZ067-068.
Flood Watch from 1 PM EST this afternoon through late tonight
for NYZ069>075-176>179.
Wind Advisory until 1 AM EST Tuesday for NYZ069-070.
Coastal Flood Advisory from 3 PM this afternoon to 9 PM EST
this evening for NYZ072-075-178.
Coastal Flood Advisory from 5 PM this afternoon to 11 PM EST
this evening for NYZ073-176.
Coastal Flood Watch from late tonight through Tuesday morning
for NYZ080-179.
Coastal Flood Advisory until 8 AM EST this morning for NYZ080-
179.
Coastal Flood Warning from 7 PM to 11 PM EST this evening for
NYZ071-078-177.
Coastal Flood Warning from 3 PM this afternoon to 7 PM EST
this evening for NYZ074.
NJ...High Wind Warning until 1 AM EST Tuesday for NJZ006-106-108.
Winter Weather Advisory from 1 PM this afternoon to 7 AM EST
Tuesday for NJZ002.
Flood Watch from 1 PM EST this afternoon through late tonight
for NJZ004-006-103>108.
Wind Advisory until 1 AM EST Tuesday for NJZ004-103>105-107.
Coastal Flood Advisory from 3 PM this afternoon to 9 PM EST
this evening for NJZ006-106-108.
MARINE...Storm Warning until 1 AM EST Tuesday for ANZ330-335-338-340-
345.
Hurricane Force Wind Warning from 1 PM this afternoon to 1 AM
EST Tuesday for ANZ350-353-355.
&&
SYNOPSIS...DW
NEAR TERM...DW
SHORT TERM...DW
LONG TERM...GC/DW
AVIATION...FEB
MARINE...DW
HYDROLOGY...DW
TIDES/COASTAL FLOODING...PW/NV